The invention relates to a light mixing device for the uniform spectral and intensity-related distribution of light coming in from an n.times.n array of optical fibers to an n.times.n array of outgoing optical fibers.
A light mixing device of this type is required, for example, for a laser warning sensor, the individual "eye" of which consists of a matrix of optical fibers "looking" into different spatial directions. In such devices, the light that is received in this "eye" from the observed space angle is to be distributed to different spectral regions. The distribution of the received light required for this purpose assumes that the complete information, that is, the contributions of each optical fiber, is present in each spectral region.
European Patent Document EP 0 241 171 As, discloses an optical coupler of the n.times.n type which comprises a plurality of 2.times.2 couplers arranged in cascade. Although this type of a coupler basically meets the above-mentioned requirements, expenditures increase if more than only four incoming or outgoing optical fibers are to be coupled with one another, as described in the embodiments of the European Patent Document EP 0 241 171 A2.
It is therefore an object of the present invention to provide a light mixing device of the above-mentioned type which has a significantly simpler and clearer construction. This object is achieved by means of a light mixing device constructed according to the present invention, in which mixer laminae, are used to widen the light beam emerging from a light source with a small diameter and beaming cone (such as in this case, the light emerging from an optical fiber), and to distribute it uniformly onto a larger radiating surface. A first stack of such mixer laminae is connected with the incoming optical fibers. A second stack of mixer laminae, on the other hand, is operated in the "reverse" manner, with light coupled from the mixer laminae into the outgoing optical fibers. The output from the first stack is coupled to the input of the second stack, with the latter stack being rotated by 90.degree. relative to the first stack.
Instead of a mixer lamina, an integrated-optical coupler of the N.times.N type may also be used, the name "N.times.N" being characteristic of the number of incoming and outgoing light channels. Such an integrated-optical coupler is essentially flat and comprises N-incoming and N-outgoing light guiding ducts on two opposite sides. By means of a number N of such couplers, which are placed on one another to form a stack, a matrix of N.sup.2 light guiding ducts will then be obtained. As mentioned above, two such stacks are then directed against one another and, turned by 90.degree. with respect to one another, are optically connected with one another.
Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of the invention when considered in conjunction with the accompanying drawings.